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Home , Cell biology, Randy Wayne (biologist)

01_P374233_PRELIMS.indd i 8/11/2009 2:35:28 PM 01_P374233_PRELIMS.indd ii 8/11/2009 2:35:28 PM Plant From Astronomy to

Randy Wayne

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Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data Wayne, Randy. Plant cell biology / . p. cm. Includes bibliographical references and index. ISBN 978-0-12-374233-9 (hardback : alk. paper) 1. — Cytology. I. Title. QK725.W39 2009 571.6’2 — dc22 2009018976 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN : 978-0-12-374233-9

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02_P374233_ITR.indd iv 8/6/2009 6:18:50 PM Dedicated to President John F. Kennedy for inspiring my generation to be courageous in the pursuit of science

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Preface xiii 2 .12 The – Plasma Membrane – 1 . On the of Cells Continuum 49 1 .1 Introduction: What Is a Cell? 1 2 .13 Summary 50 1 .2 The Basic Unit of 4 2 .14 Questions 50 1 .3 The Chemical Composition of Cells 6 3. Plasmodesmata 1 .4 A Sense of Cellular Scale 7 3 .1 The Relationship between Cells and 1 .5 The Energetics of Cells 9 the 51 1 .6 Are There Limits to the Mechanistic 3 .2 Discovery and Occurrence of View? 10 Plasmodesmata 52 1 .7 The Mechanistic Viewpoint 3 .3 of Plasmodesmata 53 and God 11 3 .4 Isolation and Composition of 1 .8 What Is Cell Biology? 12 Plasmodesmata 55 1 .9 Summary 12 3 .5 Permeability of Plasmodesmata 56 1 .10 Questions 14 3 .6 Summary 60 3 .7 Questions 60 2 . Plasma Membrane 2 .1 The Cell Boundary 15 4 . Endoplasmic Reticulum 2 .2 Topology of the Cell 15 4 .1 Significance and of the 2 .3 Evidence for the Existence of a Plasma Endoplasmic Reticulum 61 Membrane 16 4 .2 Discovery of the Endoplasmic 2 .4 Structure of the Plasma Membrane 20 Reticulum 61 2 .5 Isolation of the Plasma Membrane 23 4 .3 Structure of the Endoplasmic 2 .6 Chemical Composition of the Plasma Reticulum 62 Membrane 25 4 .4 Structural Specializations That Relate 2 .7 Transport 31 to 64 2 .8 Electrical Properties of the Plasma 4 .5 Isolation of RER and SER 65 Membrane 39 4 .6 Composition of the ER 65 2 .9 Characterization of Two Transport 4 .7 Function of the Endoplasmic of the Plasma Membrane 41 Reticulum 65 2.9.1 Proton-Pumping ATPase 41 4.7.1 Synthesis 65 2.9.2 The K ϩ Channel 44 4.7.2 Synthesis on the 2 .10 Plasma Membrane – Localized Endoplasmic Reticulum 66 Physiological Responses 47 4.7.3 Protein Glycosylation 2.10.1 Guard Cells 47 ( Synthesis) 71 2.10.2 Motor Organs 48 4.7.4 Calcium Regulation 71 2.10.3 Action Potentials 48 4.7.5 Phenylpropanoid and Flavonoid 2.10.4 Cell Polarization 48 Synthesis 73 2 .11 Structural Specializations of 4 .8 Summary 74 the Plasma Membrane 48 4 .9 Questions 74

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5. 8. Movement within the Endomembrane 5 .1 Discovery of 75 System 5 .2 Isolation of Peroxisomes 75 8 .1 Discovery of the Secretory Pathway 119 5 .3 Composition of Peroxisomes 76 8 .2 Movement to the Plasma Membrane 5 .4 Function of Peroxisomes 76 and the Extracellular Matrix 123 5.4.1 β -Oxidation 76 8.2.1 Movement between the ER 5.4.2 78 and the 124 5 .5 Relationship between 8.2.2 Movement from the Golgi and Peroxisomes 81 Apparatus to the Plasma 5 .6 Metabolite Channeling 83 Membrane 125 5 .7 Other Functions 85 8 .3 Movement from the ER to the Golgi 5 .8 Biogenesis of Peroxisomes 86 Apparatus to the 126 5 .9 Evolution of Peroxisomes 88 8 .4 Movement from the ER to the Vacuole 126 5 .10 Summary 88 8 .5 Movement from the Plasma 5 .11 Questions 88 Membrane to the Endomembranes 127 8.5.1 Fluid-Phase Endocytosis 127 6 . Golgi Apparatus 8.5.2 Receptor-Mediated Endocytosis 130 6 .1 Discovery and Structure of the 8.5.3 Piggyback Endocytosis 131 Golgi Apparatus 89 8 .6 Disruption of Intracellular Secretory 6 .2 Polarity of the Golgi Stack 91 and Endocytotic Pathways 131 6 .3 Isolation of the Golgi Apparatus 92 8 .7 Summary 132 6 .4 Composition of the Golgi Apparatus 93 8 .8 Questions 132 6 .5 Function of the Golgi Apparatus 93 6.5.1 Processing of Glycoproteins 93 9. Cytoplasmic Structure 6.5.2 Synthesis of 93 9 .1 Historical Survey of the Study of 6.5.3 Transport of Sugars 94 Cytoplasmic Structure 133 6 .6 The Mechanism of Movement from 9 .2 Chemical Composition of to Cisterna 94 Protoplasm 136 6 .7 Positioning of the Golgi Apparatus 98 9 .3 Physical Properties of 137 6 .8 Summary 99 9.3.1 Viscosity of the Cytoplasm 138 6 .9 Questions 99 9.3.2 Elasticity of the Cytoplasm 147 9 .4 Microtrabecular Lattice 148 7. The Vacuole 9.4.1 Function of the Microtrabecular 7 .1 Discovery of the Vacuole 101 Lattice in Polarity 148 7 .2 Structure, Biogenesis, and Dynamic 9 .5 Summary 149 Aspects of 102 9 .6 Questions 149 7 .3 Isolation of Vacuoles 105 7 .4 Composition of Vacuoles 106 10. Actin and Microfi lament-Mediated 7 .5 Transport across the Vacuolar Processes Membrane 108 10 .1 Discovery of Actomyosin and the 7.5.1 Proton-Translocating Pumps 109 Mechanism of Muscle Movement 151 7.5.2 ABC (ATP-Binding Cassette) 10 .2 Actin in Nonmuscle Cells 154 Transporters or Traffic ATPases 110 10.2.1 Temporal and Spatial 7.5.3 Slowly Activated Vacuolar Localization of Actin in Channels 110 Plant Cells 154 7.5.4 Water Channels 111 10.2.2 of Actin 155 7 .6 Functions of the Vacuole 111 10.2.3 Biochemistry of Myosins 157 7.6.1 Proteolysis and Recycling 111 10 .3 Force-Generating Reactions Involving 7.6.2 Taking up Space 112 Actin 157 7.6.3 Storage and 113 10.3.1 Actomyosin 157 7.6.4 Role in Turgor Generation 115 10.3.2 Polymerization of Actin 7.6.5 Other Functions 117 Filaments 158 7 .7 117 10 .4 Actin-Based Motility 158 7 .8 Summary 117 10.4.1 Cytoplasmic Streaming 159 7 .9 Questions 118 10.4.2 Movements 162

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10.4.3 Cell Plate Reorientation in 12 .5 A Kinetic Description of Regulation 189 Allium 163 12.5.1 Early History of Kinetic 10.4.4 of Vesicles Involved Studies 189 in Tip Growth and Auxin-Induced 12.5.2 Kinetics of Reactions 190 Growth 163 12.5.3 Kinetics of and 10.4.5 Contractile Vacuoles 164 Dehydration 194 10 .5 Role of Actin in 164 12.5.4 A Thermodynamic Analysis of 10 .6 Summary 164 the Signal-to-Noise Problem 196 10 .7 Questions 164 12 .6 Ca2 ϩ Signaling System 196 12 .7 Mechanics of Doing Experiments to 11 . Tubulin and -Mediated Test the Importance of Ca2 ϩ as a Processes Second Messenger 197 11 .1 Discovery of in Cilia 12 .8 Specific Signaling Systems in Plants ϩ and Flagella and the Mechanism of Involving Ca2 198 ϩ Movement 165 12.8.1 Ca 2 -Induced Secretion in 11 .2 Microtubules in Nonflagellated or Aleurone Cells 198 Nonciliated Cells and the 12.8.2 Excitation-Cessation of Discovery of Tubulin 168 Streaming Coupling in 11.2.1 Temporal and Spatial Localization Characean Internodal Cells 198 of Microtubules in and 12.8.3 Regulation of Turgor in Cells 199 Plant Cells 170 12 .9 Phosphatidylinositol Signaling System 204 11.2.2 Characterization of Microtubule- 12.9.1 Components of the System 204 Associated Motor Proteins 173 12.9.2 Phosphatidylinositol Signaling 11 .3 Force-Generating Reactions Involving in Guard Cell Movement 204 Tubulin 174 12 .10 The Role of in Cells 205 11.3.1 Sliding 174 12 .11 Summary 206 11.3.2 Polymerization/ 12 .12 Questions 206 Depolymerization 174 11 .4 Tubulin-Based Motility 175 13. 11 .5 Microtubules and Cell Shape 175 13 .1 Discovery of Chloroplasts and 11.5.1 Apical Meristems 175 207 11.5.2 Tracheary Elements 176 13.1.1 Discovery of Photosynthesis 208 11.5.3 Guard Cells 177 13.1.2 Discovery and Structure of 11.5.4 Extracellular Matrix of Chloroplasts 210 Oocystis 178 13 .2 Isolation of Chloroplasts 214 11.5.5 Mechanism of Microtubule- 13 .3 Composition of the Chloroplasts 214 Mediated Cellulose Orientation 178 13 .4 and 11.5.6 Tip-Growing Cells 178 in Photosynthesis 215 11 .6 V arious Stimuli Affect Microtubule 13.4.1 Laws of Thermodynamics 216 Orientation 179 13.4.2 Molecular Free of Some 11 .7 Microtubules and Cytoplasmic Photosynthetic Processes 217 Structure 180 13.4.3 Molecular Free Energy of 11 .8 Intermediate Filaments 180 Oxidation-Reduction 11 .9 Centrin-Based Motility 180 Reactions 218 11 .10 Tensegrity in Cells 181 13 .5 Organization of the Thylakoid 11 .11 Summary 181 Membrane and the Light Reactions of 11 .12 Questions 181 Photosynthesis 221 13.5.1 Photosystem Complexes 223 12. 13.5.2 Cytochromeb6 - f Complex 224 12 .1 The Scope of Cell Regulation 183 13.5.3 ATP Synthase 224 12 .2 What Is -Response Coupling? 184 13.5.4 Light Reactions of Photosynthesis 225 12 .3 Receptors 186 13 .6 Physiological, Biochemical, and 12 .4 Cardiac Muscle as a Paradigm for Structural of the Light Understanding the Basics of Reactions 227 Stimulus-Response Coupling 187 13 .7 of Carbon 228

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13 .8 Reduction of Nitrate and the 16 .6 280 Activation of Sulfate 230 16 .7 Chromosomal Replication 281 13 .9 Chloroplast Movements and 16 .8 Transcription 282 Photosynthesis 230 16 .9 and Formation 285 13 .10 Genetic System of 232 16 .10 Summary 287 13 .11 Biogenesis of Plastids 234 16 .11 Questions 287 13 .12 Summary 235 13 .13 Questions 236 17 . and Proteins 17 .1 Nucleic Acids and Protein Synthesis 289 14. Mitochondria 17 .2 Protein Synthesis 290 14 .1 Discovery of the Mitochondria and 17 .3 Protein Activity 294 Their Function 237 17 .4 Protein Targeting 294 14.1.1 History of the Study of 17 .5 Protein– Protein Interactions 295 Respiration 237 17 .6 Protein Degradation 295 14.1.2 History of the Structural Studies 17 .7 Structure of Proteins 296 in Mitochondria 238 17 .8 Functions of Proteins 296 14 .2 Isolation of Mitochondria 240 17 .9 Techniques of 296 14 .3 Composition of Mitochondria 241 17 .10 Plants as Bioreactors to Produce 14.3.1 Proteins 241 Proteins for Vaccines 297 14.3.2 241 17 .11 Summary 297 14 .4 Cellular Geography of Mitochondria 241 17 .12 Questions 297 14 .5 Chemical Foundation of Respiration 242 14.5.1 Fitness of ATP as a Chemical Energy Transducer 242 18. The Origin of Life 14.5.2 Glycolysis 246 18 .1 Spontaneous Generation 299 14.5.3 247 18 .2 Concept of Vitalism 300 14 .6 Other Functions of the Mitochondria 254 18 .3 The Origin of the Universe 301 14 .7 Genetic System in Mitochondria 255 18 .4 of the Early Earth 303 14 .8 Biogenesis of Mitochondria 256 18 .5 Prebiotic Evolution 304 14 .9 Summary 257 18 .6 The Earliest Darwinian Ancestor and 14 .10 Questions 257 the Last Common Ancestor 309 18 .7 Diversity in the Biological World 315 15. Origin of 18 .8 The Origin of Consciousness 316 15 .1 Autogenous Origin of Organelles 259 18 .9 Concept of Time 317 15 .2 Endosymbiotic Origin of 18 .10 Summary 317 Chloroplasts and Mitochondria 260 18 .11 Questions 318 15 .3 Origin of Peroxisomes, , and Cilia 262 19. 15 .4 Ongoing Process of Endosymbiosis 263 19 .1 319 15 .5 Primordial Host Cell 263 19.1.1 Prophase 320 15 .6 Symbiotic DNA 264 19.1.2 Prometaphase 321 15 .7 Summary 264 19.1.3 Metaphase 324 15 .8 Questions 265 19.1.4 Anaphase 326 19.1.5 Telophase 331 16. The Nucleus 19 .2 Regulation of Mitosis 331 16 .1 The Discovery of the Nucleus and 19 .3 Energetics of Mitosis 331 Its Role in Heredity, , and 19 .4 Division of Organelles 332 Development 267 19 .5 Cytokinesis 332 16 .2 Isolation of Nuclei 271 19.5.1 Cell Plate Formation 332 16 .3 Structure of the 19.5.2 Isolation of Cell Plates 334 and Matrix 271 19.5.3 Orientation of the Cell Plate 336 16 .4 of 273 19 .6 Summary 338 16 .5 Morphology of Chromatin 277 19 .7 Questions 338

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20. Extracellular Matrix 20 .8 Cell Expansion 349 20 .1 Relationship of the Extracellular 20.8.1 Forces, Pressures, and Stresses Matrix of Plant and Animal Cells 339 and Their Relationship to Strain 349 20 .2 Isolation of the Extracellular Matrix 20 .9 Summary 355 of Plants 341 20 .10 Epilog 355 20 .3 Chemical Composition and 20 .11 Questions 356 Architecture of the Extracellular Matrix 341 20 .4 Extracellular Matrix – Plasma Appendix 1 SI Units, Constants, Variables, and Membrane – Cytoskeletal Continuum 343 Geometric Formulae 357 20 .5 Biogenesis of the Extracellular Matrix 344 Appendix 2 A Cell ’s View of 20.5.1 Plasma Membrane 344 Non-Newtonian Physics 363 20.5.2 Cytoskeleton 345 Appendix 3 Calculation of the Total Transverse 20.5.3 Endomembrane System 345 Force and Its Relation to Stress 371 20.5.4 Self-Assembly of the Extracellular Appendix 4 Laboratory Exercises 373 Matrix 346 20 .6 Permeability of the Extracellular Matrix 346 Index 383 20 .7 Mechanical Properties of the Extracellular Matrix 346

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This book is in essence the lectures I give in my plant Recognizing the basic similarities between all living cell biology course at . Heretofore, the eukaryotic cells (Quekett, 1852, 1854; Huxley, 1893), I lecture notes have gone by various titles, including “ Cell discuss both animal and plant cells in my course. Although La Vie, ” “ The Book Formerly Known as Cell La Vie, ” the examples are biased toward plants (as they should be in “ Molecular Theology of the Cell, ” “ Know Thy Cell ” (with a plant cell biology course), I try to present the best exam- apologies to Socrates), “ Cell This Book ” (with apolo- ple to illustrate a process and sometimes the best examples gies to Abbie Hoffman), and “ Impressionistic Plant Cell are from animal cells. I take the approach used by August Biology. ” I would like to take this opportunity to describe Krogh (1929); that is, there are many in the this course. It is a semester-long course for undergradu- treasure house of nature and if one respects this treasure, ate and graduate students. Since the undergraduate biol- one can find an organism created to best illuminate each ogy majors are required to take , biochemistry, and principle! I try to present my course in a balanced manner, evolution as well as 1 year each of mathematics and phys- covering all aspects of plant cell biology without empha- ics, and 2 years of chemistry, I have done my best to inte- sizing any one plant, , , or technique. grate these disciplines into my teaching. Moreover, many I realize, however, that the majority of papers in plant of the students also take plant , , cell biology today are using a few model organisms and plant growth and development, plant , plant bio- “ -omic ” techniques. My students can learn about the suc- chemistry, plant , and a variety of courses cesses gained though this approach in a multitude of other that end with the suffix “ -omics ” ; I have tried to show the courses. I teach them that there are other approaches. connections between these courses and plant cell biology. Pythagoras believed in the power of numbers, and I Nonbotanists can find a good introduction to plant biology believe that the power of numbers is useful for under- in Mauseth (2009) and Taiz and Zeiger (2006). standing the nature of the cell. In my class, I apply the Much of the content has grown over the past 20 years power of numbers to help relate quantities that one wishes from the questions and insights of the students and teaching to know to things that can be easily measured (Hobson, assistants who have participated in the class. The students ’ 1923; Whitehead, 1925; Hardy, 1940; Synge, 1951, 1970; interest has been sparked by the imaginative and insight- Feynman, 1965; Schrö dinger, 1996). For example, the area of ful studies done by the worldwide of cell biolo- a rectangle is difficult to measure. However, if one knows its gists, which I had the honor of presenting. length and width, and the relation that area is the product of I have taken the approach that real divisions do not length and width, the area can be calculated from the easily exist between subject areas taught in a university, but only measurable quantities. Likewise, the circumference or area in the state of mind of the teachers and researchers. With of a circle is relatively difficult to measure. However, if one this approach, I hope that my students do not see plant cell measures the diameter and multiplies it by π, or the square of biology as an isolated subject area, but as an entré e into the diameter by π/4, one can easily obtain the circumference every aspect of human endeavor. One of the goals of my and area, respectively. In the same way, one can easily esti- course is to try to reestablish the connections that once mate the height of a tree from easily measurable quantities if existed between mathematics, astronomy, physics, chemis- one understands trigonometry and the definition of tangent. try, geology, philosophy, and biology. It is my own personal My teaching was greatly influenced by a story that attempt, and it is an ongoing process. Consequently, it is Hans Bethe told at a meeting at Cornell University com- far from complete. Even so, I try to provide the motivation memorating the 50th anniversary of the chain reaction pro- and resources for my students to weave together the threads duced by Enrico Fermi. Bethe spoke about the difference of these disciplines to create their own personal tapestry of between his graduate adviser, Arnold Sommerfeld, and the cell from the various lines of research. his postdoctoral adviser, Enrico Fermi. He said that, in the

Plant Cell Biology Copyright © 2009, Elsevier, Inc. All rights of in any form reserved. xiii

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field of atomic physics, Sommerfeld was a genius at cre- each term. Some specialized terms are essential for pre- ating a mathematical theory to describe the available data. cise communication in science just as it is in describ- Sommerfeld’s skill, however, depended on the presence of ing love and beauty. However, some terms are created data. Fermi, on the other hand, could come up with theories to hide our ignorance, and consequently prevent further even if the relevant data were not apparent. He would make inquiry, because something with an official-sounding name estimates of the data from first principles. For example, he seems well understood (Locke, 1824; Hayakawa, 1941; estimated the force of the first atomic bomb by measuring Rapoport, 1975). In Goethe’s (1808) “ Faust Part One, ” the distance small pieces of paper flew as they fell to the Mephistopheles says: “ For at the point where concepts fail. ground during the blast in Alamogordo. Knowing that the At the right time a word is thrust in there. With words we force of the blast diminished with the square of the distance fitly can our foes assail.” Francis Bacon (1620) referred to from the bomb, Fermi estimated the force of the bomb rela- this problem as the “ Idols of the Marketplace.” Often we tive to the force of . Within seconds of the blast, he think we are great thinkers when we answer a question calculated the force of the bomb to be approximately 20 with a Greek or Latin word. For example, if I am asked, kilotons, similar to which the expensive machines recorded “ Why are leaves green? ” I quickly retort, “ Because they (Fermi, 1954; Lamont, 1965). have chlorophyll.” The questioner is satisfied, and says In order to train his students to estimate things that they “ Oh. ” The conversation ends. However, chlorophyll is just did not know, Fermi would ask them, “ How many piano the Greek word for green leaf. Thus, I really answered the tuners are there in Los Angeles? ” After they looked befud- question with a tautology. I really said “ Leaves are green dled, he would say, “ You can estimate the number of piano because leaves are green ” and did not answer the question tuners from first principles! For example, how many peo- at all. It was as if I was reciting a sentence from scripture, ple are there in Los Angeles? One million? What percent- which I had committed to memory without giving it much age has pianos? Five percent? Then there are 50,000 pianos thought. However, I gave the answer in Greek, and with in Los Angeles. How often does a piano need to be tuned? authority … so it was a scientific answer. About once a year? Then 50,000 pianos need to be tuned in In “ An Essay Concerning Human Understanding, ” John a year. How many pianos can a piano tuner tune in a day? Locke (1824) admonished that words are often used in a Three? Then one tuner must spend 16,667 days a year tun- nonintellectual manner. He wrote, ing pianos. But since there are not that many days in a year, and he or she probably only works 250 days a year, then … he would not be much better than the Indian before- there must be around 67 piano tuners in Los Angeles. ” mentioned, who, saying that the world was supported by My students apply the power of numbers to the study a great elephant, was asked what the elephant rested on; of cellular processes, including membrane transport, pho- to which his answer was, a great tortoise. But being again tosynthesis, and respiration, in order to get a feel for these pressed to know what gave support to the broad-backed tor- processes and the interconversions that occur during these toise, replied, something he knew not what. And thus here, as processes between different forms of energy. My students in all other cases where we use words without having clear and distinct ideas, we talk like children; who being questioned apply the power of numbers to the study of , what such a thing is, which they know not, readily give the motion, and membrane trafficking in order to satisfactory answer, that it is something; which in truth signi- be able to postulate and evaluate the potential mechanisms fies no more, when so used either by children or men, but that involved in these processes, and the relationships between they know not what; and that the thing that they pretend to these processes and the bioenergetic events that power know and talk of is what they have no distinct idea of at all, them. Becoming facile with numbers allows the students to and so are perfectly ignorant of it, and in the dark. understand, develop, and critique theories. “ As the Greek origin of the word [theory] implies, the Theory is the true Sometimes terms are created to become the shibbo- seeing of things— the insight that should come with healthy leths of a field, and sometimes they are created for political sight ” (Adams and Whicher, 1949). reasons, financial reasons, or to transfer credit from some- Using the power of numbers to relate seemingly unre- one who discovers something to someone who renames it lated processes, my students are able to try to analyze all (Agre et al., 1995). Joseph Fruton (1992) recounted (and their conclusions in terms of first principles. They also learn translated) a story of a conversation with a famous to make predictions based on first principles. The students in Honor é de Balzac’s La Peau de Chagrin: must be explicit in terms of what they are considering to be facts, what they are considering to be the relationship “ Well, my old friend, ” said Planchette upon seeing Japhet between facts, and where they are making assumptions. This seated in an armchair and examining a precipitate, “ How provides a good entr é e into research, because the facts must goes it in chemistry?” be refined and the assumptions must be tested (East, 1923). “ It is asleep. Nothing new. The Acad émie has in the mean- I do not try to introduce any more terminology in my time recognized the existence of salicine. But salicine, aspar- class than is necessary, and I try to explain the origin of agine, vauqueline, digitaline are not new discoveries. ”

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“ If one is unable to produce new things, ” said Raphael, “ it present concepts are only the last approximation in a long seems that you are reduced to inventing new names. ” series of similar attempts which, of course, is not ended. ” “ That is indeed true, young man. ” I teach my students that it is important to be skeptical when considering old as well as new ideas. According to I teach plant cell biology with a historical approach and Thomas Gold (1989), teach “ not only of the fruits but also of the trees which have borne them, and of those who planted these trees” (Lenard, New ideas in science are not always right just because they 1906). This approach also allows them to understand the are new. Nor are the old ideas always wrong just because origins and meanings of terms; to capture the excitement they are old. A critical attitude is clearly required of every of the moment of discovery; to elucidate how we, as a sci- . But what is required is to be equally critical to the entific community, know what we know; and it empha- old ideas as to the new. Whenever the established ideas are sizes the unity and continuity of human thought (Haldane, accepted uncritically, but conflicting new evidence is brushed aside and not reported because it does not fit, then that par- 1985). I want my students to become familiar with the great ticular science is in deep trouble — and it has happened quite innovators in science and to learn their way of doing sci- often in the historical past. ence (Wayne and Staves, 1998, 2008). I want my students to learn how the we learn about choose and pose To emphasize the problem of scientists unquestioningly questions, and how they go about solving them. I do not accepting the conventional wisdom, Conrad H. Waddington want my students to know just the results and regurgitate (1977) proposed the acronym COWDUNG to signify the those results on a test (Szent-Gyö rgyi, 1964; Farber, 1969). Conventional Wisdom of the Dominant Group. I do not want my students to become scientists who merely In teaching in a historical manner, I recognize the impor- repeat on another organism the work of others. I want my tance of Thomas H. Huxley’s (1853) warnings that “ Truth students to become like the citizens of Athens, who accord- often has more than one Avatar, and whatever the forgetful- ing to Pericles “ do not imitate — but are a model to others. ” ness of men, history should be just, and not allow those who Whether or not my students become professional cell biolo- had the misfortune to be before their time to pass for that gists, I hope they forever remain amateurs and dilettantes in reason into oblivion ” and “ The world, always too happy to terms of cell biology. That is, I hope that I have helped them join in toadying the rich, and taking away the ‘ one ewe lamb’ become “ one who loves cell biology ” and “ one who delights from the poor.” Indeed, it is often difficult to determine who in cell biology” (Chargaff, 1986)— not someone who can- makes a discovery (Djerassi and Hoffmann, 2001). I try to not recognize the difference between a pile of bricks and an the best of my ability to give a fair and accurate account of edifice (Forscher, 1963), not someone who sells “ buyology ” the historical aspects of cell biology. (Wayne and Staves, 2008), and not someone who sells his or My course includes a laboratory section and my stu- her academic freedom (Rabounski, 2006; Apostol, 2007). dents perform experiments to acquire personal experience Often people think that a science course should teach in understanding the living cell and how it works (Hume, what is new, but I answer this with an amusing anec- 1748; Wilson, 1952; Ram ó n y Cajal, 1999). Justus von dote told by (1986): “ Kaiser Wilhelm I Liebig (1840) described the importance of the experimen- of Germany, Bismark’s old emperor, visited the Bonn tal approach this way: Observatory and asked the director: ‘ Well, dear Argelander, what’s new in the starry sky? ’ The director answered Nature speaks to us in a peculiar language, in the language of promptly: ‘ Does your Majesty already know the old?’ phenomena; she answers at all times the questions which are The emperor reportedly shook with laughter every time he put to her; and such questions are experiments. An experiment retold the story. ” is the expression of a thought: we are near the truth when the phenomenon, elicited by the experiment, corresponds to the According to R. John Ellis (1996), thought; while the opposite result shows that the question was falsely stated, and that the conception was erroneous. It is useful to consider the origins of a new subject for two reasons. First, it can be instructive; the history of science pro- My students cannot wait to get into the laboratory. In vides sobering take-home messages about the importance of fact, they often come in on nights and weekends to use the not ignoring observations that do not fit the prevailing con- ceptual paradigm, and about the value of thinking laterally, in microscopes to take photomicrographs. At the end of the case apparently unrelated phenomena conceal common prin- semester, the students come over to my house for dinner ciples. Second, once a new idea has become accepted there (I worked my way through college as a cook) and bring is often a tendency to believe that it was obvious all along— their best photomicrographs. After dinner, they vote on the hindsight is a wonderful thing, but the problem is that it is twelve best, and those are incorporated into a class cal- never around when you need it! endar. The calendars are beautiful and the students often make extra to give as gifts. The historical approach is necessary, in the words of In 1952, Edgar Bright Wilson Jr. wrote in An George Palade (1963), “ to indicate that recent findings and Introduction to Scientific Research, “ There is no excuse for

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doing a given job in an expensive way when it can be car- the people who they consider to be the best scientists. This ried through equally effectively with less expenditure.” is a shame. They read the work of others … but not the best. Today, with an emphasis on research that can garner sig- Interestingly, they usually are well read when it comes to nificant money for a college or university through indirect reading the best writers (e.g., Shakespeare, Faulkner, etc.). costs, there is an emphasis on the first use of expensive Typically , the people on my students ’ lists of best scien- techniques to answer cell biological questions and often tists have written books for the layperson or an autobiogra- questions that have already been answered. However, the phy (Wayne and Staves, 1998). Even Isaac Newton wrote very expense of the techniques often prevents one from a book for the layperson! I give my class these references performing the preliminary experiments necessary to learn and encourage them to become familiar with their favorite how to do the experiment so that meaningful and valuable scientists first hand. The goal of my lectures and this book data and not just lists are generated. Unfortunately, the lists is to facilitate my students ’ personal and continual journey generated with expensive techniques often require statisti- in the study of life. cians and computer programmers, who are far removed My goal in teaching plant cell biology is not only to from experiencing the living cells through observation and help my students understand the mechanisms of the cell measurement, to tell the scientist which entries on the list and its organelles in converting energy and material mat- are meaningful. Thus, there is a potential for the distinction ter into a living organism that performs all the functions between meaningful science and meaningless science to we ascribe to life. I also hope to deepen my students’ ideas become a blur. I use John Synge’s (1951) essay on vicious of the meaning, beauty, and value of life and the value in circles to help my students realize that there is a need to searching for meaning and understanding in all processes distinguish for themselves what is fundamental and what is involved in living. derived. I thank Mark Staves and my family, Michelle, Katherine, By contrast, this book emphasizes the importance of the Zack, Beth, Scott, my mother and father, and aunts and scientists who have made the great discoveries in cell biol- uncles, for their support over the years. I also thank my col- ogy using relatively low-tech quantitative and observational leagues at Cornell University and teachers at the Universities methods. But— and this is a big but — these scientists also of , Georgia, and California at Los Angeles, treated their brains, eyes, and hands as highly developed sci- and especially Peter Hepler and Masashi Tazawa, who taught entific instruments. I want my students to have the ability to me how to see the universe in a living cell. get to know these great scientists. I ask them to name who they think are the 10 best scientists who ever lived. Then I Randy Wayne, ask if they have ever read any of their original work. In the Department of Plant Biology, Cornell University majority of the cases, they have never read a single work by

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